Field of the Disclosure
The present application relates to an organic light emitting diode display device and a driving method thereof.
Description of the Related Art
Recently, a variety of flat panel display (FPD) devices adapted to reduce weight and volume corresponding to disadvantages of cathode ray tube (CRT) are being developed. The flat panel display devices include liquid crystal display (LCD) devices, field emission display (FED) devices, plasma display panels (PDPs), electroluminescence devices and so on.
The PDPs have advantages such as simple structure, simple manufacture procedure, lightness and thinness, and are easy to provide a large-sized screen. In view of these points, the PDPs attract public attention. However, the PDPs have serious problems such as low light emission efficiency, low brightness and high power consumption. Also, thin film transistor LCD devices use thin film transistors as switching elements. Such thin film transistor LCD devices are being widely used as the flat display devices. However, the thin film transistor LCD devices have disadvantages such as a narrow viewing angle and a low response time, because of being non-luminous devices. Meanwhile, the electroluminescence display devices are classified into an inorganic light emitting diode display device and an organic light emitting diode display device on the basis of the formation material of a light emission layer. The organic light emitting diode display device corresponding to a self-illuminating display device has features such as high response time, high light emission efficiency, high brightness and wide viewing angle.
The organic light emitting diode display device controls a voltage between a gate electrode and a source electrode of a driving transistor. As such, a current flowing from a drain electrode of the driving transistor toward a source electrode of the driving transistor can be controlled.
The current passing through the drain and source electrodes of the driving transistor is applied to an organic light emitting diode and allows the organic light emitting diode to emit light. Light emission quantity of the organic light emitting diode can be controlled by adjusting the current quantity flowing into the organic light emitting diode.
The current applied to the organic light emitting diode is largely affected with a threshold voltage Vth and mobility of the driving transistor. As such, methods of compensating for the threshold voltage and mobility of the driving transistor are being researched and applied. Nevertheless, the current flowing through the organic light emitting diode can be varied due to deterioration degree of the organic light emitting diode. In accordance therewith, the current of the organic light emitting diode must be compensated on the basis of a sensed deterioration degree of the organic light emitting diode. However, it is difficult to detect the deterioration degree of the organic light emitting diode. This results from the fact that properties of the driving transistor are reflected to the sensed information when the deterioration degree of the organic light emitting diode is sensed.
To address this matter, external compensation methods of sensing and compensating the properties of the driving transistor and the threshold voltage of the organic light emitting diode are being researched and applied. The external compensation method sensing the threshold voltage and mobility of the driving transistor and the deterioration degree of the organic light emitting diode must require a large number of memories.
Also, the properties of the driving transistor and the organic light emitting diode is sensed and reflected into a compensation data. To this end, the sensed data must be transferred to a timing controller. Then, the sensed data can be skewed. Due to this, errors can be generated in the sensed data and the compensation data.
In order to solve this problem, a method of controlling a delay time is being used. However, the delay control method cannot sense real-time data (or variations) generated at a real (or normal) operation not an initial setup operation.